Hearing devices are wearable hearing apparatuses which are used to assist the hard-of-hearing. In order to accommodate numerous individual requirements, various types of hearing devices are available such as behind-the-ear (BTE) hearing devices and in-the-ear (ITE) hearing devices, for example also concha hearing devices or completely-in-the-canal (ITE, CIC) hearing devices. The hearing devices listed as examples are worn on the outer ear or in the auditory canal. Bone conduction hearing aids, implantable or vibrotactile hearing aids are also available on the market. The damaged hearing is thus stimulated either mechanically or electrically.
The key components of hearing devices are principally an input converter, an amplifier and an output converter. The input converter is normally a receiving transducer e.g. a microphone and/or an electromagnetic receiver, e.g. an induction coil. The output converter is most frequently realized as an electroacoustic converter e.g. a miniature loudspeaker, or as an electromechanical converter e.g. a bone conduction hearing aid. The amplifier is usually integrated into a signal processing unit. This basic configuration is illustrated in FIG. 1 using the example of a behind-the-ear hearing device. One or a plurality of microphones 2 for recording ambient sound are built into a hearing device housing 1 to be worn behind the ear. A signal processing unit 3 which is also integrated into the hearing device housing 1 processes and amplifies the microphone signals. The output signal for the signal processing unit 3 is transmitted to a loudspeaker or receiver 4, which outputs an acoustic signal. Sound is transmitted through a sound tube, which is affixed in the auditory canal by means of an otoplastic, to the device wearer's eardrum. Power for the hearing device and in particular for the signal processing unit 3 is supplied by means of a battery 5 which is also integrated in the hearing device housing 1.
An ITE hearing device adjusted to a user generally consists of a lower part (shell) and an upper part (face plate and/or casing). After assembling the shell and/or casing with corresponding hearing device components, the casing and/or the upper part is adhered to the shell. It is necessary for both parts to rest closely against one another so that no foreign objects can enter the hearing device.
Hearing device shells, but also casings, are frequently produced using stereolithography methods (SLA). However, after this production step, they have to be smoothed, i.e. grinded or polished, but also coated if necessary. These method steps can be implemented in a so-called tumbling machine. In this way, the entire surface of the work piece is treated. Surfaces and edges are thus also abraded, which is undesirable in these cases. However, following their manufacture, the openings for components, but also the openings to which the housing parts are added, are in particular no longer allowed to be damaged or destroyed.
DE 10 2005 013 834 A1 discloses a method for producing a hearing aid component and a corresponding hearing aid component in which a stereolithography method is used for production purposes.
According to internal sources, only the lower parts, i.e. the shells, are currently produced using stereolithography methods. Here the cutting edge, to which the shell with the casing is added, is reinforced with material, so that various polishing and smoothing methods can be carried out without any problem. In a subsequent manual work step, the surplus material must then be removed.
The upper part, namely the faceplate, is currently typically manufactured as an injection-molded plate. No tumbling process is needed here. After adhering the casing and/or the face plate to the shell, protruding parts of the casing must be cut off manually. This represents a very high outlay in respect of the production of a hearing device.